The long-term goal of this proposal is to develop a treatment for the central nervous system (CNS) pathology of highly progressive lysosomal enzyme deficiencies. The treatment must be broadly applicable and lead to a permanent stable cure. The Mucopolysaccharidosis Type VII (MRS VII) mouse, lacking the lysosomal enzyme beta-glucuronidase (GUS), is uniquely suited to these goals because of the well-characterized CNS involvement. Restoration of GUS by normal bone marrow transplantation (BMT) or by enzyme replacement therapy (ERT) is therapeutic to visceral organs and tissues when performed early in development. The replaced enzyme restores cell function by completing digestion of accumulated/stored substrates. Both approaches are broadly applicable to lysosomal storage diseases (LSD) in general, which occur in nearly 1 in 5,000 live births. The CNS of many LSD have storage material that does not respond well to BMT and ERT. Discovery of CNS engraftable neuronal stem cells (NSC) which generate progeny that migrate to multiple regions of brain raises hope for treating the CNS. Obstacles include NSC source/availability and immune rejection of incompatible cells. NSC can be cultured from umbilical cord blood (CB) and bone marrow (BM), providing sources less controversial than fetal tissue. Aim 1 tests the hypothesis that ectopic Noggin treatment improves the efficiency of NSC development from murine adult BM and/or fetal liver (the murine equivalent of CB) during in vitro culture. Noggin antagonizes bone morphogenic proteins, causing increased neuronal versus hematopoietic cell development. Aim 2 tests the hypothesis that costimulatory blockade will establish host tolerance to CNS grafted allogeneic NSC. Even if CB proves to be a reliable source for generating NSC, differences in major (or minor) histocompatibility complex antigens could stimulate immune rejection. Aim 2 will determine how efficiently host immunity rejects allogeneic BM and fetal liver derived NSC when transplanted into brain with and without reagents that enable successful allogeneic BMT by blocking costimulatory activation of immune cells. Aim 3 will determine the therapeutic potential of normal BM and fetal liver derived NSC as well as MPS VII BM derived NSC lentivirally transduced with GUS cDNA. The latter approach simulates use of the patients own BM to avoid both source/availability and immunological barriers to NSC therapy. The aims of this proposal address several important barriers to successful treatment of diseases of the CNS. The knowledge gained will provided valuable information towards successful replacement of missing or defective cells and/or proteins needed by the brain for normal healthy function. Discovery of methods to circumvent barriers to CNS cellular engraftment is relevant to progressive CNS diseases that not only include LSD, but also Parkinson's and Alzheimer's diseases. [unreadable] [unreadable] [unreadable]